Two new species of deep-bodied Paleozoic actinopterygians, Aesopichthys erinaceus gen. nov., sp. nov. and Proceramala montanensis gen. nov., sp. nov., are described from the Upper Chesterian, Upper Mississippian (Namurian E2b, Lower Carboniferous) Bear Gulch Limestone of Montana, USA, and the new family Aesopichthyidae is erected for them. These two fishes share features usually associated with deep body and deep head specializations, particularly in Palaeoniscimorpha, such as a shortened gape, tall maxilla, vertical suspensorium, deepened flank scales and an elongate dorsal fin. Aesopichthys in particular, for which more complete information is known, also possessed a suite of very specialized adaptations in feeding mechanism, ganoine sculpturing, fin form, and cranial defensive structures that have strong ethological implications. These features include small mobile premaxillae, a spinous and apparently rotatable posteroventral infraorbital, lobed pectoral base, and partially webbed pectoral, dorsal, anal and caudal fins.

Within a general scheme of interrelationships of primitive actinopterygians, these two new taxa pertain to Palaeoniscimorpha, i.e., basal Actinopteri. Then, from a cladistic analysis limited, beside these two new taxa, to Wendyichthys and Cyranorhis (two other already described actinopterygians from Bear Gulch), Platysomus, and Cheirolepis, it appears that the Aesopichthyidae display no close relationship to the Platysomidae but should be the sister group of the Rhadinichthyid-group i.e., [Cyranorhis [Rhadinichthyidae Wendyichthys]].

New cranial material of Mesturus cordillera Martill et al., 1998 from the Oxfordian of Quebrada del Profeta locality of northern Chile allows a detailed study of the jaw apparatus and some additional cranial bones. The tooth morphology in combination with a short and pyriform edentulous maxilla refers the species to the pycnodont fish genus Gyrodus Agassiz, 1833. The available material is not sufficient for a specific determination. therefore, the taxon is left as Gyrodus sp. (=Mesturus cordillera). This is the first species of Gyrodus known from the Upper Jurassic of South America. A second Gyrodus species, G. macrophthalmus cubensis Gregory, 1923, is known from the Upper Jurassic of Cuba. The stratigraphic and biogeographic occurrences of Gyrodus are discussed and the genus Mesturus Wagner, 1862 is thus restricted to the Jurassic of Europe.

Skeletal remains attributable to large dissorophoid amphibians, including four femora, two humeri, and an isolated palatine bone, have recently been recovered from the Lower Permian fissure fill deposits at Richards Spur, Oklahoma. Three of the femora are assignable to Acheloma cumminsi. One humerus represents an indeterminate trematopid, perhaps A. cumminsi, whereas the remaining humerus and femur are evidently of dissorophid origin and probably assignable to Cacops. The palatine bone is of unusual morphology and evidently represents a third distinct large dissorophoid taxon. Although the Richards Spur faunal assemblage is unquestionably dominated by small animals such as Captorhinus aguti, Cardiocephalus, and Euryodus, the discovery of rare, larger skeletal elements at the site implies that some elements of the fauna approached or slightly exceeded a body length of about one meter. Although probably uncommon in the vicinity of the fissures, such larger species were clearly not excluded from the deposits by preservational biases. Like other taxa known from Richards Spur, the dissorophoids were fully terrestrial as adults, and their presence reinforces previous interpretations of the Richards Spur paleoenvironment as an arid highland region. However, some Richards Spur taxa have also been reported from lowland “deltaic” localities such as South Grandfield, Oklahoma, implying that their distribution was more cosmopolitan.

In the thirty years since the last comprehensive review of the Brachyopidae many new brachyopid genera have been described and several different phylogenies proposed. This paper provides revised diagnoses of the Brachyopidae, their sister taxon, the Chigutisauridae, and the Brachyopoidea, erects a new higher taxon, Brachyopomorpha to include stem brachyopoids, and reviews the status of all material referred at one time to these taxa. In it we present revised illustrations of the first described member of the Brachyopidae and clarify parts of the morphology of it and other members of the Brachyopoidea including especially the mandible and postcranial skeleton. A new genus and species, Vigilius wellesi, is proposed for the skull of Hadrokkosaurus bradyi as the holotype of H. bradyi, a mandible, cannot be positively associated with the skull. A phylogenetic analysis including most taxa and all putative outgroups confirms the Chigutisauridae as sister group to the Brachyopidae, forming the Brachyopoidea. Bothriceps australis becomes a sister taxon to the Brachyopoidea. Xenobrachyops allos and Keratobrachyops australis are the most plesiomorphic members of the Brachyopidae and Chigutisauridae respectively.

A new genus and species of stereospondyl temnospondyl, Nanolania anatopretia, is described from the Early Triassic Arcadia Formation (Rewan Group) of Queensland, Australia. N. anatopretia has several character states that suggest it belongs to the group of derived trematosaurian stereospondyls that include the Rhytidosteidae and Brachyopoidea. These include the absence of a lacrimal, an untwisted quadrate ramus of the pterygoid, and a shallow otic notch. It is tentatively referred to the Rhytidosteidae. N. anatopretia is the third temnospondyl taxon from the Arcadia Formation to be represented by a skull less than 50 mm long. The others are the basal stereospondyl Lapillopsis nana, and juveniles of the capitosaurid Parotosuchus aliciae. Given that Lapillopsis nana and Nanolania anatopretia are not known from any larger specimens, and that the temnospondyl fauna from the Arcadia Formation has been well sampled, it is suggested that they are species that never grew large. It seems quite likely that a diverse array of small temnospondyls lived alongside the larger temnospondyls of the Triassic elsewhere in the world but have not been discovered due to biases working against the preservation and collection of small temnospondyl specimens.

Vertebrate remains from the Late Albian–Early Cenomanian Candeleros Formation of northwestern Patagonia include those of a pipoid frog, which is described herein. The fossils consist of partially articulated and disarticulated elements, some of them badly broken, that are mostly exposed in ventral aspect. The description is based on one incomplete skeleton that presumably belongs to a single individual; this specimen possesses a combination of character states not present in other known non-palaeobatrachid pipimorph taxa and is identified here as a new genus and species, Avitabatrachus uliana. The species is moderately small (estimated snout-vent length ca. 35 mm) and shares with Pipidae conch-like squamosals, deeply excavated prootics to form channels for the Eustachian tubes, articulations for the lower jaws at the anterolateral corners of otic capsules, and fused sacrum and urostyle. Avitabatrachus possesses at least eight presacral vertebrae, the first two of which are fused, with flat, opisthocoelous centra. Unique features of this taxon are the presence of parasagittal flanges along the posterior halves of the otic capsules and the wide transverse processes of the posterior presacral vertebrae, which are only slightly anteriorly directed. Preliminary comparisons with other fossil pipoid taxa in the context of recent parsimony analyses suggest that it is the sister taxon of Pipidae. However, this phylogenetic placement of the new taxon should be corroborated in a future rigorous analysis that should include some putative stem pipid taxa that currently are being restudied.

A revision of gomphodont cynodonts from the Chañares Formation of Argentina, is presented. Four species in two genera: Massetognathus pascuali, M. teruggii, M. major, and Megagomphodon oligodens were originally described by Romer in 1967 and 1972. Qualitative characters proposed originally as diagnostic of the species were revised, and a bivariate analysis of allometry of 17 linear skull measurements was performed upon 31 specimens. Allometry relationships account for most of the differences among specimens. There are neither size gaps nor systematic trends across the sample. The temporal region scales with a ′positive′ allometry, whereas components of the neurocranium and muzzle show ′negative′ or isometric scaling. This results in a change from short, stocky skulls with large muzzles in small specimens, to slender skulls with small muzzles and large temporal fossae characteristic of large individuals. The reduction and ontogenetic loss of the parietal foramen in a cynodont is reported for the first time. Consideration of qualitative characters together with the allometric results lead us to conclude that all forms belong to a single species in a growth series. Consequently, Massetognathus pascuali is recognized as the only valid entity, an idea previously suggested but without a justification based upon extensive analysis.

The first thalattosaur from the marine Middle Triassic of Guizhou Province, southern China, is described, and its phylogenetic relationships analyzed. The taxon, Anshunsaurus huangguoshuensis, was found to be the sister-taxon of Askeptosaurus italicus from the southern Alpine Triassic. The paleobiogeography of thalattosaurs, now known from the Middle and Late Triassic of China, Europe, and North America, is discussed.

The skull of the basal anomodont therapsid Anomocephalus africanus, from the Tapinocephalus Assemblage Zone of the Beaufort Group, Upper Permian of South Africa, is described in detail. Anomocephalus is characterized by the possession of two premaxillary teeth, blunted, peg-like anterior teeth, cheek teeth with saddle-shaped tips, and the presence of a tall coronoid process. Anomocephalus is the most basal member of Anomodontia because it lacks three unambiguous and six ambiguous synapomorphies present in all other anomodonts. This basal position provides compelling support for the hypothesis that anomodonts originated in Gondwana and later dispersed into Euramerica and elsewhere across Pangea. Minimum divergence times suggest strongly that anomodonts were diversifying in central Gondwana well before the onset of Beaufort sedimentation. Accordingly, the absence of terrestrial vertebrates in the Ecca Group is most likely an artifact of preservational bias.

Acid preparation, at the Natural History Museum, London, of a turtle skull and jaw presented to the Museum of Geology, Sandown, Isle of Wight, England, by R. W. Harris in 1931, has revealed extremely derived palatal morphology previously undescribed in turtles. The specimen is described as a new genus and species, Sandownia harrisi, and is superficially similar to certain soft-shelled turtles (family Trionychidae) although the extensive secondary palate and extensive skull roof are previously unknown for this family. Other features of the skull suggest that it is not a trionychid but can be assigned to the Trionychoidea and that its closest affinities are with the members of the Trionychia (Carettochelyidae and Trionychidae). This specimen is one of the oldest known cryptodiran turtles that nests within the living families (the Polycryptodira). It suggests that the deep divergences among the living families of the Cryptodira occurred more than 110 million years ago.

The rollers (Aves: Coraciiformes sensu stricto) from the Middle Eocene of Messel (Hessen, Germany) and the Upper Eocene of the Quercy (France) are described. The “Messel-roller” Eocoracias brachyptera, gen. et sp. nov. is the earliest certain record of rollers known so far and is classified within the new family Eocoraciidae. New excavations in the Quercy and a revision of the earlier collections have produced additional skeletal material which can be assigned to Geranopterus alatus Milne-Edwards, 1892. This species so far has been known from an isolated humerus only. A new species, Geranopterus milneedwardsi, is described from the Upper Eocene of the Quercy and mainly differs from G. alatus in its smaller size. The genus Geranopterus is classified within the new family Geranopteridae which is shown to be the sister taxon of the two recent families Brachypteraciidae and Coraciidae. The Eocoraciidae are the sister taxon of the Coracioidea (Geranopteridae and recent rollers). Outgroup comparison with the basal rollers described in this study suggests that the fairly long wing of the Coraciidae and the elongated tarsometatarsus of the Brachypteraciidae are derived features of these families.

The recently discovered Cretaceous asioryctithere Ukhaatherium nessovi, represented by three individuals with virtually complete postcrania, shows basal character states for Eutheria, that were previously only partially known from the fragmentary postcranium of Asioryctes nemegetensis. A new suite of ankle characters is revealed. This suite renders characters previously considered as present in the hypothetical common ancestor of eutherians, as diagnostic of a more nested group in the mammalian tree. Some possible primitive retentions preserved in one or both asioryctitheres are the absence of a pulley-shaped astragalar trochlea, fibula only slightly encasing the astragalus laterally, absence of an anterior plantar tubercle on the calcaneum, and presence of a ventrally curved tuber calcis (straight in most other eutherians).

A set of characters in the ankle joints were plotted on a phylogenetic tree of basal therian taxa, including among others, the mentioned asioryctitheres, Vincelestes neuquenianus, Deltatheridium pretrituberculare, Mayulestes ferox, and Pucadelphys andinus. The states in the hypothetical ancestors of Theria, Metatheria, and Eutheria were inferred with the maximum parsimony algorithm. Derived states of the ankle of Eutheria are fewer, and the hypothetical ancestors of Metatheria and Eutheria turn out to be more similar to each other than previously suspected.

A new fossil odontocete genus and species, Numataphocoena yamashitai is from the Early Pliocene Horokaoshirarika Formation, Numata, central Hokkaido, Japan. The porpoise was probably buried in relatively shallow marine sediments. This specimen consists of an incomplete skull, a right periotic and tympanic bulla, a posterior part of the right mandible, 23 isolated teeth, a nearly complete vertebral column, a chevron, incomplete right and well-preserved left scapulae, a right forelimb including humerus, radius, ulna, and a few indetermined carpals, and several ribs, all the same individual. The ankylosis of the epiphyses to vertebral bodies and to long bones, such as humerus, radius and ulna, shows that this individual reached both sexual and physical maturity; the animal in life was probably about 220 cm long. The cranial vertex has an elevated frontal knob, and the tooth crown is spatulated; both are characteristic of phocoenids. Numataphocoena yamashitai shows many primitive features such as premaxillae with less atrophied posterior extremities extending far posteriorly almost to hinder margin of the narial fossa, robust zygomatic processes, a periotic with massive anterior process and rugose posterior process, humerus long relative to radius or ulna, and free cervical vertebrae. The axial skeleton is significantly different from that of extant relatives in its a small number of vertebrae with anteroposteriorly broad transverse processes, and a long humerus relative to the radius and ulna.

For many years the primitive extinct toothed whale genus Patriocetus has been known only from the holotype partial skull of P. ehrlichi (van Beneden, 1865), and a more nearly complete paratype skull, both from uppermost Oligocene sands near Linz, Austria, in the western Paratethys region. A virtually complete skull found in Late Oligocene beds on the Mangyshlak Peninsula of the Republic of Kazakhstan in the 1960s is the first specimen of Patriocetus known from the eastern Paratethys region, extending the range of this genus approximately 4,000 km eastward from the type locality of the genus at Linz. Herein named Patriocetus kazakhstanicus, this new species of Patriocetus differs from P. ehrlichi in size, morphology, and dental count. Direct comparison of the holotype skull of P. kazakhstanicus to that of P. ehrlichi has provided a more accurate definition of the arrangement of the bones in the skull roof of P. ehrlichi, long a source of uncertainty because sediment cemented to the surface of both the holotype and the paratype of the latter species partially obscures the sutures, making it difficult to determine the boundaries of the frontals, parietals, and supraoccipital. The skull of P. kazakhstanicus also shares well-defined generic characters with the partial skull of an undescribed species of Patriocetus from Germany (Rothausen and Sanders, in preparation), for which there are casts of the complete skull. The rostra of those two specimens are more nearly complete than those of the holotype and the paratype of P. ehrlichi, each of which is missing the anterior end of the rostrum. All four specimens share similarities in dentition and rostral characters that now confirm Rothausen's (1968) conclusions that members of the genus Patriocetus were longirostrine forms.

A new genus and species of Toxodontidae from the Huayquerian (late Miocene) of El Cajón Valley (Catamarca, Argentina) is described. Calchaquitherium mixtum gen. et sp. nov. (Toxodontinae) is characterized by a combination of features of different genera, being closest to Mixotoxodon, Xotodon, and Nonotherium. Cladistic analysis of the family Toxodontidae has been attempted in order to assess the phylogenetic relationships of the new taxon. Four genera of the families Leontiniidae and Notohippidae were used as outgroups. The five subfamilies previously included in Toxodontidae do not represent monophyletic groups according to this analysis. A new classification of Toxodontidae, with two subfamilies, Nesodontinae and Toxodontinae, with three main groups of genera within the latter, is proposed.

The mylodontid ground sloths (Xenarthra, Tardigrada) are among the most intriguing components of the Lujanian (Late Pleistocene-Early Holocene) fauna of the Pampean region in South America. Limb proportions and resistance to bending forces were studied in Scelidotherium, Glossotherium and Lestodon to infer their locomotory abilities. Body masses were estimated using scale and computer-generated geometric models. Allometric equations were calculated from humeri, ulnae, radii, femora, tibiae, and the pes, and were used to predict linear dimensions from body mass. Slopes and intercepts were obtained using Model I and II regressions. An indicator of strength was calculated for humeri and femora. Body masses of approximately 850, 1,500 and 4,100 kg were estimated from scale models for Scelidotherium, Glossotherium and Lestodon, respectively. The proportions and capacity to resist bending forces of the limb bones of Scelidotherium and Glossotherium indicate that they were well adapted for strenuous activities in which force is enhanced over velocity, such as digging. We consider these taxa as possible builders of the large Late Cenozoic burrows present in the Pampean region. Although limb proportions of Lestodon are comparable to those of the others, its low strength indicator suggests that its limbs were not as well designed to perform such strenuous activity.